1. Field of the Invention
The present invention relates to industrial automation systems and, more particularly, to a communication device and method for transmitting data within an industrial automation system.
2. Description of the Related Art
Industrial automation systems are used to monitor, control and regulate technical processes, in particular in the field of production, process and building automation, and make it possible to operate control devices, sensors, machines and industrial installations in a manner that is intended to be as autonomous as possible and independent of human interventions. On account of the continuously increasing importance of information technology for automation systems comprising numerous networked control or computer units, methods for reliably providing functions distributed over an automation system to provide monitoring, control and regulating functions are becoming increasingly important.
Interruptions in communication connections between computer units of an industrial automation system or automation devices may result in undesirable or unnecessary repetition of transmission of a service request. This causes additional utilization of communication connections of the industrial automation system, which may result in further system disruptions or faults. In addition, untransmitted messages or incompletely transmitted messages may prevent an industrial automation system from changing to or remaining in a safe operating state, for example. This may ultimately result in failure of a complete production installation and in a costly production standstill. A particular problem regularly results in industrial automation systems from message traffic with comparatively numerous but relatively short messages, thus intensifying the above problems.
EP 1 770 458 A2 describes an industrial automation system having at least one programmable logic control unit in which a configuration unit for configuring the control unit and for announcing its availability to a communication network is provided. Here, the configuration unit allocates a unique communication network address, which may be an IPv6 address, for example, to the control unit. The control unit can be automatically activated in this manner.
EP 14171757.9 discloses a method for allocating communication network addresses for network subscribers of a segmented network having a plurality of subnetworks. The subnetworks are each connected, via a subnetwork router, to a collection network that interconnects them. Here, the subnetwork routers determine a common address space in a decentralized manner by interchanging router messages distributed over the collection network, and communication network addresses for the network subscribers are stipulated inside the address space.
Internet Engineering Task Force (IETF), Request for Comments (RFC) 6145 and 6146, ISSN 2070-1721, April 2011, describes conversion of Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) communication connections based on Internet Protocol, version 6 (IPv6) to communication connections based on Internet Protocol, version 4 (IPv4). In this case, such conversion is referred to as NAT64 (Network Address Translation). IPv6-based communication devices can access IPv4-based communication devices via NAT by performing address format adaptation, in particular. Within the scope of NAT64, IPv6 communication devices use virtual IPv6 addresses to access IPv4 communication devices, where the virtual IPv6 addresses are replaced with IPv4 addresses assigned to the IPv4 communication devices using an NAT64 server. Communication network addresses for return channels from IPv4 communication devices to IPv6 communication devices are translated in a similar manner.
In addition, IETF, RFC 6147, discloses the practice of calculating associated IPv6 address entries (AAAA Resource Records) from IPv4 address entries, which are referred to as A Resource Records (RR), in a Domain Name System (DNS) and of providing these associated IPv6 address entries via DNS servers. Derivation of AAAA Resource Records from A Records can fundamentally be performed manually by a DNS administrator, can be planned using an IP Address Management (IPAM) solution or can be continuously determined automatically using DNS64 servers.